1. Field of the Invention
The present invention relates to an insulated wire with a noise-suppressing function, and more particularly, to an insulated wire with a noise-suppressing function used for a signal line.
2. Description of the Related Art
A known method for suppressing high-frequency noise which has entered a signal line is shown in FIG. 9. In the method, two divided core pieces 81a and 81b are accommodated in a cylindrical case 82 which can be divided into two sections. An insulated wire 83 is sandwiched by the two core pieces 81a and 81b. A ring-shaped magnetic core 81 formed by the divided core pieces 81a and 81b is secured to the periphery of the insulated wire 83 by the use of case fasteners 82a and 82b provided for the case 82. An advantage of this method is that the ring-shaped magnetic core 81 can be easily placed on the insulated wire 83 afterwards.
Another known method is shown in FIGS. 10 and 11, in which an insulated wire 83 is inserted into a ring-shaped magnetic core 91 and the ring-shaped magnetic core 91 is covered by a resin material 93 to secure the core to the insulated wire 83. An advantage of this method is that the user cannot easily remove the ring-shaped core 91 from the insulated wire 83 and this ensures that high-frequency noise is positively suppressed.
In the configurations shown in FIGS. 9 and 10, however, since the insulated wire 83 is inserted into the ring-shaped magnetic cores 81 and 91, the inner diameters of the cores 81 and 91 need to be set larger than the outer diameter of the insulated wire 83. Therefore, large and heavy ring-shaped magnetic cores 81 and 91 have to be used in order to obtain the desired noise suppression effect.